12. JSF Core Tag Reference

f:subview

The Subview tag creates a naming container (a container component with a
unique identifier) that contains all JavaServer Faces core and custom tags on a
nested page via "jsp:include" or any tag that dynamically includes another page
from the same web application, such as JSTL's "c:import".

The subview tag
wraps JSF components contained in an included JSP or Facelets page that allows
nested views. One advantage of this tag is that include files can be reused.
Since JSF requires a unique ID for each component, the subview tag creates a
unique "namespace" for child components.